diff --git a/src/hqt/tmux/runner.py b/src/hqt/tmux/runner.py
index 25e0cbb..5311352 100644
--- a/src/hqt/tmux/runner.py
+++ b/src/hqt/tmux/runner.py
@@ -1,5 +1,6 @@
 import asyncio
 import logging
+import shlex
 from dataclasses import dataclass
 
 log = logging.getLogger(__name__)
@@ -315,6 +316,68 @@ class TmuxRunner:
 
         return window_id
 
+    async def new_aux_window(
+        self, name: str, cwd: str, command: list[str], label: str
+    ) -> str | None:
+        """Create an auxiliary (non-session) tool window and switch to it.
+
+        Appends at the next free index, then styles by window_id — not name — so
+        duplicate names (tool windows are spawned fresh every time) stay
+        unambiguous. Deliberately does NOT set remain-on-exit: the window closes
+        when the tool exits (a quit shell closes its window too). The window is
+        never tracked by hqt; it lives purely as a tmux window.
+
+        Returns the window_id, or None on failure (the half-created window is
+        cleaned up).
+        """
+        idx = await self._next_window_index()
+        args = [
+            "new-window",
+            "-t",
+            f"{self.session_name}:{idx}",
+            "-n",
+            name,
+            "-c",
+            cwd,
+            "-P",
+            "-F",
+            "#{window_id}",
+        ]
+        if command:
+            args.append(shlex.join(command))
+        rc, stdout, err = await self._exec(*args)
+        if rc != 0:
+            log.error("new-window (aux) failed: %s", err)
+            return None
+        window_id = stdout.strip()
+
+        # Style by window_id: automatic-rename off, the @hqt_label, then the
+        # Frappé per-window theme — one atomic invocation (";" argv separators).
+        rc, _, err = await self._exec(
+            "set-option",
+            "-w",
+            "-t",
+            window_id,
+            "automatic-rename",
+            "off",
+            ";",
+            "set-option",
+            "-w",
+            "-t",
+            window_id,
+            "@hqt_label",
+            label,
+            ";",
+            *_window_theme_args(window_id),
+        )
+        if rc != 0:
+            log.error("set-option (aux window) failed for %s: %s", name, err)
+            await self._exec("kill-window", "-t", window_id)
+            return None
+
+        await self._exec("select-window", "-t", window_id)
+        return window_id
+
     async def has_window(self, window_name: str) -> bool:
         """Check if a window with this name exists."""
         rc, stdout, _ = await self._exec(
diff --git a/tests/test_tmux.py b/tests/test_tmux.py
index 2b48878..9d08fc8 100644
--- a/tests/test_tmux.py
+++ b/tests/test_tmux.py
@@ -1009,3 +1009,63 @@ async def test_poll_info_empty_names(runner):
     result = await mgr.poll_info([])
     assert result == {}
     assert runner._exec.call_count == 1
+
+
+# ---------------------------------------------------------------------------
+# Task 2: new_aux_window — styled tool windows (never tracked)
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_new_aux_window_spawns_styles_and_selects(runner):
+    runner._exec.side_effect = [
+        (0, "0\n", ""),   # _next_window_index: indices [0] -> next index 1
+        (0, "@7\n", ""),  # new-window -P -F '#{window_id}'
+        (0, "", ""),      # set-option (automatic-rename + @hqt_label + theme)
+        (0, "", ""),      # select-window
+    ]
+    wid = await runner.new_aux_window("lazygit", "/proj", ["lazygit"], "lazygit · proj")
+    assert wid == "@7"
+
+    calls = runner._exec.call_args_list
+    # new-window: next free index, name, cwd, print window_id, then the command.
+    assert calls[1].args == (
+        "new-window", "-t", "hqt-main:1", "-n", "lazygit",
+        "-c", "/proj", "-P", "-F", "#{window_id}", "lazygit",
+    )
+    # post-creation options target the window_id and NEVER set remain-on-exit.
+    assert calls[2].args[:6] == (
+        "set-option", "-w", "-t", "@7", "automatic-rename", "off",
+    )
+    assert "@hqt_label" in calls[2].args
+    assert "lazygit · proj" in calls[2].args
+    assert "remain-on-exit" not in calls[2].args
+    # switch to it.
+    assert calls[3].args == ("select-window", "-t", "@7")
+
+
+@pytest.mark.asyncio
+async def test_new_aux_window_shell_omits_command_arg(runner):
+    runner._exec.side_effect = [
+        (0, "2\n", ""),   # indices [2] -> next index 3
+        (0, "@9\n", ""),
+        (0, "", ""),
+        (0, "", ""),
+    ]
+    wid = await runner.new_aux_window("shell", "/proj", [], "shell · proj")
+    assert wid == "@9"
+    calls = runner._exec.call_args_list
+    assert calls[1].args == (
+        "new-window", "-t", "hqt-main:3", "-n", "shell",
+        "-c", "/proj", "-P", "-F", "#{window_id}",
+    )
+
+
+@pytest.mark.asyncio
+async def test_new_aux_window_returns_none_when_new_window_fails(runner):
+    runner._exec.side_effect = [
+        (0, "0\n", ""),    # next index
+        (1, "", "boom"),   # new-window fails
+    ]
+    wid = await runner.new_aux_window("nvim", "/p", ["nvim"], "nvim · p")
+    assert wid is None